macOS notifications

To send a Notification Center notification, run this command through bash:

message="..."
osascript -e 'on run argv' \
  -e 'display notification (item 1 of argv) with title "Pi"' \
  -e 'end run' \
  -- "$message"

Use the requested message as message. This sends a native macOS Notification Center notification without opening a window. For it to remain visible until dismissed, set the sending app's notification style to Alerts in System Settings → Notifications; Banners disappear automatically.